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Life Cycle > LC Exam 2 Fertilization and Implantation > Flashcards

LC Exam 2 Fertilization and Implantation Flashcards

1
Q

Sperm head components

A

Haploid, condensed chromatin
Protamines (specialized histones)
Acrosome

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2
Q

Sperm tail components

A

9+2 axoneme structure

Kartagener’s -> dyenin dysfxn and no motility

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3
Q

Oocyte suspension

A

Up to 45 years
Meiotic Prophase 1
As oocyte number decreases so does quality

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4
Q

Zona pellucida

A

Barrier - egg not exposed to environment until rupture
Glycoprotein sheet: ZP1, ZP2, ZP3
Mostly protein
Sperm bind to ZP
Mutations: mutations could lead to impossible penetration

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5
Q

Sperm requirements

A

Sufficient number, motility, morphology
Capacitation: acquire ability to undergo acrosome rxn
Binds ZP3

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6
Q

Fertilization steps

A 
Ovulation
Sperm deposition
Sperm capacitance
Binding to ZP
Acrosome rxn
Sperm-oocyte fusion
Oocyte activation
Male/female pronuclei formation
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7
Q

Acrosome reaction

A

Membrane fusion and exocytosis

Release of hyalurdonidase and acrosin

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8
Q

Sperm-oocyte fusion and oocyte reaction

A

Fusion mediated by fertilin
Calcium plays large role
Zona reaction leads to cortical granule release and changes ZP3 which are now not capable of binding sperm

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9
Q

Completion of fertilization

A

Second meiotic divsion/polar body
Pronuclei formation
Polar bodies still visible

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10
Q

Oocyte activation

A

First meiotic division completed upon LH surge
Meiosis I arrested in prOphase I until Ovulation
Fert/reawakening results in second meiotic division
Meiosis II arrested in METaphase II until MET sperm

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11
Q

Early blastocyst and chr screening

A

Still has thin zona pellucida
Trophoblast (not inner cell mass) is biopsied for chr/genetic abnormalities
Can also screen anuplodies
Can’t always account for mosaicism
Some places have started using polar body (no info on male, bad for AR phenotypes)

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12
Q 
Semen analysis
Volume
Concentration
Motility
Morphology
A 
Volume: >1.5ml
Concentration: >15x10^6
Motility: >32%
Morphology: 4% normal
(Based on population of fertile men, not all pop based)
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13
Q

Problems on semen analysis:
CF
Testosterone

A

CF: no sperm, secretions clog and degenerate vas
T: decrease sperm count, use as contraceptive?
Need to repeat a few months apart

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14
Q

Female evaluation of fertility

A 
How many eggs remaining
Fertility = quantity and quality
Blood tests: E2, FSH (increases with age), check beginning of cycle
AMH (any time)
US: check eggs in ovary
Can't check blood on OCP
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15
Q

Increasing maternal age

A

Proportion of euploid embryos declines with age

Large drop late 30’s approaching 40

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16
Q

Role of progesterone

A

Secreted by corpus luteum (maintained initally by ßhCG from blastocyst)
Triggers decidualization via cAMP

17
Q

Decidua: characteristics and layers

A

Accumulation of glycogen and lipid
PRL, IGF1BP, and PGE2 (via COX2) production
Recruitment of dNK cells
Basalis, capsularis, parietalis (eventually uterine cavity is abolished as cap and par come into contact)

18
Q

Factors that ready endometrium

A

Prime time: day 20-24 of menstrual cycle
Decreased E2 -> decreased proliferation
Decidua formation/consolidation

19
Q

Stages of implantation:

A

Apposition: interdigitation of microvili, pinopod binding
Attachment: actual binding of blastocyst and epi
Invasion: triggers pronounced decidualization
decidua closes behind blastocyst

20
Q

Normal implantation sites

Abnormal implantation

A

Usually posterior uterine, near fundus
Placenta previa: covers cervix
Placenta accreta: implants further in wall, post C-section
Ectopic implantation: most common is tube/ampulla

21
Q

Prevention of immune attack on fetus

A

Syncytiotrophoblasts: no MHC
Extravilious trophoblast: HLA-C,G, E
Therefore no large influx of B/T cells
HLA-G may downregulate?

22
Q

Prevention of immune attack on fetus

A

Syncytiotrophoblasts: no MHC
Extravilious trophoblast: HLA-C,G, E
Therefore no large influx of B/T cells
HLA-G may downregulate?

23
Q

hCG detection

A

Embryo: Cycle day 18
Maternal blood: 3 weeks (day 21)
Maternal urine: 4 weeks (day 28)

24
Q

hCG detection (produced by?)
Normal rise
Ectopic rise

A

Produced by trophoblast
Embryo: Cycle day 18
Maternal blood: 3 weeks after cycle day 1
Maternal urine: 4 weeks after cycle day 1
Doubles every 48 hours
Ectopic: faster than expected rise
Ectopic: levels >1500-2000 w/out uterine presence

25
Q

Heterotopic pregnancy

A

More common with IVF

Mixed uterine and ectopic pregnancy

26
Q

Ectopic treatment

A

Methotrexate - targets dividing cells
Surgical: otomy vs. oscopy
Expectant: if hCG is declining on own (rare)

Life Cycle (21 decks)

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